Battery energy storage systems (BESSs) containing one or more batteries are used in many applications. For instance, such systems are used in telecom applications, power generation applications, electric grid applications, and/or energy management applications. As a BESS is used for a given application and the batteries therein age, the batteries may need to be balanced with respect to their states of charge. The state of charge (SOC) of a battery, as used herein, is generally defined as the percentage of the full capacity of a battery that is still available for further discharge. Thus, the SOC of a battery may be used to regulate charging and discharging of the battery.
Conventionally, systems for charging energy storage systems are configured to implement an active maintenance operation in order to perform required maintenance activities on each energy storage system (e.g., resetting of the state-of-charge (SOC) of each energy storage system). This active maintenance operation is typically performed at a given frequency based on a timing device or countdown timer associated with each energy storage system. For example, in response to the expiration of the countdown timer associated with a given energy storage system, the system is taken offline to reset its SOC to a top-of-charge (TOC) state (e.g. a 100% SOC) and/or to conduct an open circuit voltage check on the system. As a result, during the performance of an active maintenance operation, the energy storage system is unavailable for power delivery, which is undesirable.
In view of the aforementioned issues, an improved system and method for performing maintenance on an energy storage farm would be welcomed in the technology.